Brauneis U, Vassilev P M, Quinn S J, Williams G H, Tillotson D L
Department of Physiology, Boston University School of Medicine 02118.
Am J Physiol. 1991 May;260(5 Pt 1):E772-9. doi: 10.1152/ajpendo.1991.260.5.E772.
Angiotensin II (ANG II) is a principal secretagogue of adrenal zona glomerulosa (ZG) cells. The transduction process includes a depolarization of the plasma membrane and the activation of calcium influx. The ANG II-induced depolarization is associated with an increase in total membrane resistance. To directly address the mechanism underlying these observations, we examined the effect of ANG II on K+ currents of rat, bovine, and human ZG cells, using whole cell patch clamp. Although some differences were seen in the characteristics of K+ currents between species, ANG II consistently blocked outward currents in ZG cells [rat: 47.1 +/- 4.5% (SE), n = 17; bovine: 38.6 +/- 3.3%, n = 21; and human: 13-63%, n = 3]. With the use of the cell-attached mode, single-channel recordings in bovine ZG cells demonstrated K+ channels that were reversibly blocked when ANG II was added to the bath solution. This indicates that the block of K+ channels by ANG II involves a diffusible intracellular messenger rather than a direct receptor-channel interaction. The decreased conductance of K+ can account for the ANG II-induced membrane depolarization.
血管紧张素II（ANG II）是肾上腺球状带（ZG）细胞的主要促分泌素。转导过程包括质膜去极化和钙内流的激活。ANG II诱导的去极化与总膜电阻增加有关。为了直接探究这些观察结果背后的机制，我们使用全细胞膜片钳技术研究了ANG II对大鼠、牛和人ZG细胞钾离子电流的影响。尽管不同物种间钾离子电流特性存在一些差异，但ANG II始终能阻断ZG细胞的外向电流[大鼠：47.1±4.5%（标准误），n = 17；牛：38.6±3.3%，n = 21；人：13 - 63%，n = 3]。采用细胞贴附模式，在牛ZG细胞中进行的单通道记录显示，当向浴槽溶液中添加ANG II时，钾离子通道会被可逆性阻断。这表明ANG II对钾离子通道的阻断涉及一种可扩散的细胞内信使，而非直接的受体 - 通道相互作用。钾离子电导降低可解释ANG II诱导的膜去极化现象。
